Nature of the Problem and the Committee's Approach
Declining marine fishery catches—including fish, crustaceans, and molluscs—have been the subject of much recent attention in the media and the technical literature (e.g., Botsford et al. 1997, Merrett and Haedrich 1997). For example, Atlantic halibut (Hippoglossus hippoglossus), once common off New England, are now rare. Marbled rockcod (Notothenia rossi) have been seriously depleted in the Southern Ocean. Off New Zealand, orange rough (Hoplostethus atlanticus) populations have been significantly reduced because until recently, they were fished faster than they could replace themselves. Declines in bluefin tuna (Thunnus thynnus) populations in the North Atlantic are the subject of controversy and concern. Some fisheries have been subject to severe curtailment and closure; in North America, most notably cod (Gadus morhua) off Newfoundland, groundfish off New England, and some salmon species in the Pacific Northwest. Atlantic salmon (Salmo salar) and American shad (Alosa sapidissima) have largely or completely disappeared from many rivers of the eastern eliminated from an area of the Bering Sea that lies in international waters (the Donut Hole), and many coral-reef fish species in the Philippines have disappeared from commercial catches. International disputes over fishery resources sometimes have a militaristic character, as illustrated by the "cod war" between the United Kingdom and Iceland in the 1960s and the Canadian arrest of a Spanish trawler on the high seas in the 1990s.
Sometimes, populations not directly fished might be affected. For example, yellowfin tuna (Thunnus albacares) fisheries in the eastern tropical Pacific until recent decades were responsible for the killing of perhaps hundreds of thousands
of dolphins each year. The overall yield of the world's marine capture fisheries has not grown much in recent years. Not all fisheries are in decline, however. Some fisheries have been conducted for many years without depleting the fished populations, and some previously depleted fisheries have recovered.
How serious is the problem of declining marine fishery catches? Are we seeing only local depletions, with no significant effects on global catches? Or are the localized declines symptomatic or omens of a larger problem? Are other components of marine ecosystems being seriously affected, perhaps even to the point of significantly affecting ecosystem structure and functioning? To what degree are observed changes caused by environmental fluctuations and to what degree are they caused by human activities, particularly fishing? If the problems are significant, as they appear to be or likely to become, can an ecosystem approach to fishery management help achieve sustainability of marine fisheries?
To address these and related questions, the Ocean Studies Board (OSB) of the National Research Council (NRC) established the Committee on Ecosystem Management for Sustainable Marine Fisheries. The committee was charged to ''assess the current state of fisheries resources; the basis for success and failure in marine fisheries management (including the role of science); and the implications of fishery activities to ecosystem structure and function. Each activity [was to] be considered relative to sustaining populations of fish and other marine resources" (Statement of Task). The committee, composed of experts in ecology, fishery biology, fishery management, economics, and anthropology, included members from academe, government, the fishing industry, and a nongovernmental organization.
The committee met five times over the course of its study. Its second meeting included an international conference in Monterey, California, in February 1996. The committee based its deliberations in part on the papers presented at that meeting (see Appendix A), many of which were published in a special issue of Ecological Applications (Vol. 8 Supplement, 1998). In addition, the committee reviewed a great deal of published literature, and the members contributed their own expertise and experience.
Fishery management and this report need to be seen in their broader contexts. The world's human population continues to grow, and thus the demand for food—including seafood—continues to grow as well. Marine capture fisheries yielded a total of 84 million metric tons in 1995, by far the largest contributor to the 14 kg of fish available as food per person in 1995 (FAO 1997a).
Fisheries are a large international business. In 1996, first-sale revenues from fishery products (including aquaculture and both marine and freshwater production) were worth about $U.S. 100 billion (FAO 1996a); in 1992 they provided approximately 19 percent of the total human consumption of animal protein
(FAO 1992). Fisheries provided direct and indirect employment for about 200 million people (Garcia and Newton 1997). In addition, recreational fisheries account for large direct and indirect expenditures, especially in North America, Sweden, Australasia, and elsewhere.
The industrialization occurring in many parts of the world increases the need for foreign currency, and one way to get that currency is to sell seafood. Net fisheries exports in developing countries were worth $U.S. 16 billion in 1994 (FAO 1997a), more than the exports of coffee, bananas, rice, and many other commodities (FAO 1997b). As various fished populations decline, prices can rise. All these factors can increase fishing pressure. Recreational fishing also accounts for large landings, especially for a few game species in North America. In addition, the growing human population, increasingly industrialized, affects the terrestrial and marine environments in many ways, some of which might increase the fisheries catches, but many do not. As described in Chapter 3, destruction of spawning and nursery habitats, disruption of food webs, nutrient and other chemical pollution, and sedimentation can all adversely affect fisheries. Thus, the possibility of increasing global marine fishery catches by increasing fishing effort seems increasingly remote. Indeed, it appears likely that we will need to reduce effort to sustain the current catch rate.
Society's way of looking at marine environments also has changed. International agreements reached over the past two decades increasingly recognize the importance of marine ecosystems, the need to sustain them, and the vital links between terrestrial and marine systems. People are increasingly aware of the effects of fishing on other ecosystem components such as dolphins, turtles, birds, many invertebrates, and others. The value of the goods and services provided by ecosystems is increasingly being recognized. For example, Costanza et al. (1997) estimated the world's ecosystem services at $U.S. 16 trillion to 54 trillion per year, with more than half that value derived from marine ecosystems.
Marine ecosystem services operate over a wide range of spatial and temporal scales. They range from climate regulation, operating at the global scale, to more local services such as the provision of habitat for nursery or spawning grounds or the protection of shorelines from battering by waves. Kelp forests, mangroves, coastal wetlands, and coral reefs provide habitats and protect shorelines from erosion. Estuaries and mangroves trap sediment, thus protecting downstream ecosystems such as coral reefs. Microbes in sediments can detoxify many pollutants, and others are sequestered by the sediments. In addition to food, goods include chemicals like algin and carrageenan from seaweeds. Other services, such as biogeochemical cycling in the oceans, are obviously important, although we know little of their details. Ecosystem values include many nonmarket ones, such as opportunities for recreation and aesthetic enjoyment, as well as the ecosystem services described above (Daily 1997). Some even accrue from merely knowing that the ecosystems and their components exist, even though most people will never see them. There is increasing recognition that sustaining fishery yields
will require sustaining the ecosystems that produce the fish. Moreover, there are compelling reasons beyond fishing to sustain marine ecosystems. Thus, this report is about sustaining ecosystems rather than sustaining only fishery catches.
Sustainability and Ecosystem-Based Management
In establishing the Committee on Ecosystem Management for Sustainable Marine Fisheries, the NRC and OSB recognized that the challenge of achieving sustainable fisheries is greater than the challenge of achieving a sustainable catch of each important commercial species over the next decade or two—a daunting task in itself. Because there is evidence (reviewed in Chapter 3) that the ecosystems in which exploited species live can be affected by fishing and that changes in those ecosystems can affect the exploited species, it was apparent to the committee that achieving sustainable fisheries would require a broader approach to fishery management than has been common: an ecosystem-based approach. Addressing this question, however, requires some agreement on the meaning of two terms, sustainability and ecosystem-based management.
Sustainability is an important idea, although it is hard to define precisely. The central idea is that a resource is used in such a way that it is not depleted or permanently damaged. In other words, use of the resource can be continued indefinitely. Defining the limits of "depletion," "permanent damage," "indefinitely," and related terms is difficult (Norgaard 1994), in part because the physical and biological components of the world keep changing. Nonetheless, the committee agrees that the concept provides a useful goal. To implement the goal, it is critical to understand the distinction between maintaining a particular catch rate over a short period as opposed to maintaining the continued productivity of the ecosystem, which is required to produce the species of interest (and others). Therefore, for the purposes of this report, the committee defines sustainable fisheries to be fishing activities that do not cause or lead to undesirable changes in biological and economic productivity, biological diversity, or ecosystem structure and functioning from one human generation to the next (see Lubchenco et al. 1991); sustainable fishing does not lead to ecological changes that foreclose options for future generations.
Sustainable fishing can take place at different levels of productivity and abundance of many species: in many places, fish populations have been over-fished with little change in abundance for long periods. In addition, there are many cases in which the biological and economic productivity of fish populations, ecosystems, and fisheries would be enhanced if the fish populations were allowed to rebuild; this would represent a change from one year to the next. In those cases, the goal the committee is referring to includes rebuilding of those
populations and at least some recovery of the ecosystems. The committee recognizes that environmental fluctuations and minor or short-term changes caused by fishing will continue to occur. But the goal implied by the definition above seems clear, as has a failure to achieve it in many cases thus far.
Although ecosystem management has many definitions, sustainability is a central part of most of them (Christensen et al. 1996, NRC 1996a). We cannot really manage ecosystems per se; instead, it is human activities that are managed. The committee therefore uses the term ecosystem-based management.
To the degree that it is successful, management that focuses on ecosystem structure and functioning will also improve the sustainability of fisheries. Similarly, making fishing sustainable will help to sustain marine ecosystems, albeit altered from their pre-exploitation states. But current scientific knowledge does not permit us to manage large marine ecosystems comprehensively and reliably. Therefore, by ecosystem-based management for fisheries, this committee means an approach that seriously takes all major ecosystem components and services—both structural and functional—into account in managing fisheries and one that is committed to understanding larger ecosystem processes for the goal of achieving sustainability in fishery management.
Concepts of ecosystem management and sustainability are not new, although their explicit incorporation into many management goals is fairly recent. For example, Kurien (1998) described traditional Asian coastal proverbs that used to guide traditional fishing activities. Two of them are closely related to the ideas of sustainability and ecosystem management: The wealth of the sea belongs to the dead, the living, and those yet to be born and Where is water there is fish; if we take care of the water, the fish will take care of us.
Humans as Ecosystem Components
That humans are components of the ecosystems they inhabit and use seems obvious, but it is often overlooked. Too often, managers divide the world into "the ecosystem" and "the users of the ecosystem." Such a division is artificial and can lead to the absurd conclusion that the best way to achieve sustainability of an ecosystem is to keep people out of it. Humans are integral parts of the ecosystems they inhabit and use, and their actions on land and in the oceans affect the ecosystems, just as changes in those ecosystems affect humans. Sustainability applies to them as well as to other ecosystem components.
Evolution of Views of Fishery Management
Fishing is an old activity, and concern about its effects also is old. As early as the fourteenth century, people in England were worried about fishing with a wondyrchaum (a fine-meshed trawl), which they feared was killing enormous numbers of small fish (March 1970). By 1716, minimum mesh sizes and minimum size limits for various fish species were in effect. Many forms of fishery management have evolved based on traditional knowledge gained by fishing peoples. They included cultural practices, community agreements, and government controls. But in general, and despite early regulations, management of marine fisheries was minimal before the middle of the twentieth century, with a few notable exceptions such as the International Pacific Halibut Commission (Bell 1978).
Although there has long been concern over the effects of fishing, that concern—like fishing itself—was largely confined to coastal waters until recently. The famous scientist Thomas Huxley expressed his opinion in 1883 that probably "all the great sea-fisheries are inexhaustible" (Smith 1994), although some great sea-fisheries were already depleted by then. The Atlantic halibut fishery had collapsed by the early 1880s (Goode and Collins 1887) and has not yet recovered. And the U.S. Fish Commission had been established a dozen years earlier (1871) to find the causes of declining New England fisheries.
By 1919, W.F. Thompson (1919) recognized that sea fisheries were not inexhaustible, but he identified a difficulty that remains critical to this day: "Proof that seeks to modify the ways of commerce or of sport must be overwhelming." He developed research to concentrate on what "is necessary to the perpetuation and prosperity of the fishery." To protect the Pacific halibut (Hippoglossus stenolepis) from the fate of the Atlantic halibut, the International (United States and Canada) Pacific Halibut Commission was established in 1924 with "a competent man as director of investigations": W.F. Thompson (Babcock et al. 1928). While and before Thompson was investigating the North Pacific halibut fishery, Heincke was developing catch-curve analyses as a basis for proposed minimum size limits for North Sea plaice (Pleuronectes platessa) and demonstrating racial differences in North Sea herring (Smith 1994). The International Council for the Exploration of the Seas was formed in 1902, motivated by the desire to understand and predict fluctuations in fish stocks (Smith 1994).
North Sea fish increased in size and numbers during both World Wars I and II, because naval action forced a reduction in fishing. That phenomenon led to wider recognition that fishing did affect fish stocks and that the effects were at least partly reversible. Those observations led Graham (1935, 1943) to explain how increases in fishing power allowed catches to be maintained or increased even when fish stocks declined, leading to a waste of time and
money by comparison with fishing at a maximum sustained yield.1 Gordon (1954) provided the economic theory to support Graham's observations.
In the 1950s and 1960s, scientific methods of stock assessment and estimation of fishery yields were developed based on growth rates and age composition of the catch (e.g., Ricker 1954, 1958; Beverton and Holt 1957, Murphy 1965, Gulland 1965). At the same time, fishing vessels based many hundreds or thousands of miles from fishing grounds ("distant-water fleets") changed the face of fishery management, leading to exclusive economic zones, international treaties, international fishery-management bodies, and continued international disputes about fishing. One of those international bodies, the U.S.-Canadian International Commission for Northwest Atlantic Fisheries, implemented an early attempt at incorporating ecosystem management into fisheries. When it set catch limits for a particular species, it took into account the expected bycatch of that species in fisheries for other species. It also concluded that the total sustainable catch rate for all species was less than the sum of sustainable catch rates for the individual species.
As described in Chapter 4, many factors have reduced the effectiveness of management and prevented the adoption of scientific advice. In a few cases the advice itself was not correct. Progress in developing better scientific perspectives for management and more equitable and effective ways of implementing management goals continues, but it has been slow. In some cases the obstacles seem to be overwhelming. Significant societal, commercial, and governmental economic incentives and pressures often lead to unsustainable fishing practices. It is difficult, for example, for a poor, hungry family to stop or even reduce fishing if its basic food needs depend on fishing and it has no resources with which to supplement reduced food from fishing. In addition, most such families live in countries whose governments have limited resources to apply to the problem. In wealthier societies, economic pressures can be as great as the basic need for food. But it is clear that the long-term costs of overexploitation of fishery resources are even greater than the short-term costs of reducing catches. Options for achieving sustainable fishing are the topic of this report.
As views of fishery management evolve, the importance of terms becomes apparent. For example, it is common to refer to fishing as "harvesting the resource." But the term harvest usually includes the idea that an investment has been made in a crop, which is not true of most marine-capture fisheries. Another
Maximum sustainable yield (MSY) is the largest average catch that can be captured from a stock under existing environmental conditions (NRC 1998a). Maximum economic yield (MEY) is the level of catch that provides the maximum net economic benefits or profits to society (Clark 1990, NMFS 1996b). MEY is usually less than MSY. Economic factors that influence fishing are discussed in Chapter 4.
term often used is underutilized, which implies that greater exploitation of a particular fish stock is desirable. This term probably reflects one purpose of many fishery-management institutions—that is to promote fisheries. In this report those terms and some others are avoided; in general, the committee has sought to use the terms catch or landings instead of harvest and lightly fished or subject to low fishing mortality rather than underutilized. The term stock might be linked by analogy to stock of a commodity. It also is difficult to define biologically, and so the committee has used the term population where possible. It is extremely difficult to find terms that do not express any societal values. Thoughtful evaluation of the values implicit in many terms and replacement of some of them could be an important part of achieving sustainable fishery management.
Chapter 2 sets the stage by reviewing information on the state of marine fisheries. The committee attempted to be comprehensive although not exhaustive. Thus, enough information is presented for a general overview, but not all relevant examples are discussed. In Chapter 3 the effects on ecosystems of fishing and of environmental changes are discussed. Chapter 4 describes what is known about the factors that contribute to the conditions described in chapters 2 and 3. These include incomplete scientific information, scientific errors, failure to heed scientific advice, conflicting and unresolved goals and values, failure to consider all ecosystem components, institutional failures, social and economic incentives that do not favor sustainable resource use, changes in perspectives, new information, and perhaps a failure to recognize the limits of science.
Chapter 5 applies the lessons learned in Chapter 4. The discussion covers the potential usefulness and practical application of an ecosystem-based approach, alternative institutional structures, social and economic arrangements that hold promise for improving sustainable fishing, marine protected areas, scientific questions, and research needs. The emerging recognition that marine ecosystems have values in addition to their production of food and the importance of that recognition in developing ecosystem-based approaches to sustainable fishery management are also discussed. Finally, Chapter 6 contains the committee's conclusions and recommendations.